This invention relates generally to a six-sided carton which is formed from a generally rigid, unitary, foldable, sheet like blank of an expanded polymeric material, and more particularly to a carton of such character in which at least some of the corners are sealed by means which are a part of such blank to seal the contents of the carton and to thereby prevent the egress of the contents of the carton and the entry of oxygen and moisture from the atmosphere into the carton.
It is quite common to utilize a six-sided carton which is formed by folding a generally rigid, unitary, foldable, sheet like blank of paperboard or other fibrous material for many packaging applications, for example in the packaging of breakfast cereals and in the packaging of powdered laundry detergents. These cartons usually require separate means to help prevent the contents of the carton from escaping through the gaps or spaces which are normally formed at the corners of such cartons, and to help prevent oxygen and moisture from the atmosphere from attacking the contents of the carton. Such separate means may take the form, for example, of a separate sealed bag which, is placed in the carton and in which in turn, the packaged product is placed.
Generally rigid polymeric materials, including expanded or foamed polymeric materials, offer many advantages over paperboard as a material of construction, including attractive appearance, relatively low cost, moisture imperviousness and good strength and rigidity characteristics in relationship to thickness and weight, and for these reasons these materials have captured important segments of packaging markets which were once held by paperboard. To date, however, polymeric materials have not been able to displace paperboard or other fibrous materials as the material of construction for folding boxes or cartons for breakfast cereals and other dry or particulate products to any great extent, at least in part due to the problems which relate to the sealing of the corners of such cartons.